Such a windshield wiper commonly consists of a windshield wiper blade which comprises a mounting means carrying a wiping strip which sweeps against a glazed surface in direct contact with the latter, the glazed surface (or swept surface) being for example a windshield or rear window of an automotive vehicle. The wiper blade is typically carried by a windshield wiper arm, which is arranged to be driven in alternating rotational movement by a driving spindle which is fixed on to the bodywork of the vehicle.
For aesthetic and aerodynamic reasons, it is arranged that at least the windshield wiper arm is enclosed at least partly by a cowling or streamlining element. More particularly, this cowling, having the general cross sectional shape of an inverted U-shaped channel, is secured to the windshield wiper arm in such a way that the wing portions of the U-shaped channel will be directed towards the swept surface, thus masking the windshield wiper arm. By virtue of this streamlining means, it is possible to confer on the windshield wiper a generally pleasing appearance, while also giving it an aerodynamic function such that any air flow that may penetrate into the free space existing between the swept surface and the wiper itself will be deflected away from this space, thus avoiding impairment of good operation of the wiper.
Certain drawbacks have however been encountered, in particular when the general shape of the arm is not straight, and more especially where the arm is in two portions, each of which is substantially rectilinear, but which define between them an angle greater than zero and constituting an elbow at the intersection of the two straight portions. In that arrangement, the streamlining element carried by the arm extends in the same general direction as that of the arm, being again provided with an elbow.
Thus, during a mechanical operation on the windshield wiper, for example changing the wiper blade, or during manual wiping of the glass, it is necessary to place the wiper in a disengaged position. In order to reach this position, the end of the windshield wiper arm, carried by a pivot axis which is provided on the driving head that is coupled with the driving spindle, pivots (in known manner) with respect to the driving spindle, in such a way as to space its other end, i.e. the end carrying the windshield wiper blade, away from the swept surface in a movement which is substantially perpendicular to the latter. The disengaged position is that which is reached at the end of this movement, in which the windshield wiper itself remains in a position spaced away from the swept surface.
After carrying out an operation on the wiper, or after manual wiping of the swept surface, the operator generally pushes the windshield wiper back in the reverse direction, without shifting it manually in such a way as to place the wiper in an operating position in which the blade, and more particularly its wiping strip, is actually in contact with the swept surface.
During contact of the windshield wiper blade on the swept surface, and because of the kinetic energy generated by the pivoting movement of the assembly of the arm (with its blade and streamlining element) about the pivot axis, the junction zones or elbows between the two straight portions of the arm and those of the streamlining element continue their movements towards the swept surface until they collide with it. The end of the arm carrying the blade then becomes fixed by engagement of the blade on the glazed swept surface.
Similarly, when the windshield wiper is carried by the rear tailgate of an automotive vehicle, the impact mentioned above can also take place while the tailgate is being closed sharply on its hinges, particularly when it is being slammed.
This impact on the swept surface not only produces a disagreeable noise, but can lead to damage, either to the streamlining element or to the glazed surface, thus detracting from good visibility by the driver.